LUT technology: manufacturing of printed circuit boards.

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LUT on the contrary

How to make a printed circuit board at home. Or LUT (laser ironing technology) - vice versa.

By “LUT” we mean thermal transfer of toner from paper to the metallization surface of the future printed circuit board.

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Preface

I tried many times to make a printed circuit board using LUT, but I never managed to get a reliable, easily repeatable result. In addition, when making a board, I need etched holes in the pads no larger than 0.5 mm in size. Subsequently, I use them when drilling, in order to center a drill with a diameter of 0.75 mm.

Defects manifest themselves in the form of a shift or change in the width of the tracks, as well as in the unequal thickness of the toner remaining on the copper foil after removing the paper. In addition, when removing the paper before etching, it is problematic to clean every hole in the toner of any cellulose residue. As a result, when etching a printed circuit board, additional difficulties arise, which were avoided only by doing the opposite.

I assume that the reason causing the marriage is the following.

Paper, when heated to a high temperature, begins to warp. While the temperature of foil fiberglass is always slightly lower. The toner partially adheres to the foil, but remains melted on the paper side. When warped, the paper moves and changes the original shape of the conductors.

LUT is the opposite.

At the very beginning, I want to warn you that the technology is not without certain disadvantages.

The first is the lack of special paper for thermal transfer, instead of which I suggest choosing suitable paper for self-adhesive labels. Unfortunately, not all paper is suitable. You need to choose one whose labels are denser and the backing has a good, smooth surface.

The second disadvantage is that the size of the printed circuit board is limited by the size of the soleplate of the iron. In addition, not every iron can heat foil fiberglass laminate evenly enough, so it is better to choose the most massive one.

The essence of the change in the traditional process is that it is proposed to heat not the paper with toner, but the foil fiberglass itself.

The main advantage is that with this method it is easy to control the temperature in the toner melting zone. In addition, the rubber roller allows you to evenly distribute the pressure and prevent crushing of the toner. (I write everywhere about foil fiberglass, since I have not tested other materials).

The technology is equally well suited for foil fiberglass laminate of different thicknesses, but it is better to use material no thicker than one millimeter, as it is easy to cut with scissors.

So, we take a piece of the most shabby foil fiberglass laminate and process it with sandpaper. You should not use very large sandpaper, as it can damage future tracks. However, you don’t have to sand it if you have a piece of new fiberglass. The copper surface must be thoroughly cleaned and degreased in any case.

Making a stencil for thermal transfer. To do this, we cut off the required piece from a sheet of paper for labels and separate the labels themselves from the backing. You should leave a piece of label at the beginning of the sheet to prevent the backing from getting stuck in the printer mechanism.

Do not touch with your hands the areas on the substrate where toner will subsequently be applied.

If the thickness of the foil fiberglass laminate is one millimeter or less, then the distance between the edges of the individual boards can be chosen to be 0.2 mm; if it is larger and you are going to cut the workpiece with a hacksaw, then 1.5-2.0 mm, depending on the thickness of the blade and the processing tolerance.

I use the toner layer that is installed by default in the printer driver, but “B & W Halftones:” (B/W Halftone) should be selected “Solid”. In other words, you need to prevent the appearance of a raster. You may not see it on the stencil, but it may affect the thickness of the toner.

We fix the stencil on a piece of foil fiberglass paper clips. We attach another paper clip to the free edge of the stencil so that it does not come into contact with the iron.

The melting point of different brands of toner is approximately 160-180C. Therefore, the temperature of the iron should be slightly higher by 10-20C. If your iron does not heat up to a temperature of 180C, then you will have to adjust it.

Before heating, the soleplate of the iron should be thoroughly cleaned of grease and other contaminants!

We heat the iron to a temperature of 180-190 degrees and press it tightly against the foil fiberglass as shown in the figure. If you position the iron differently, the board may heat up too unevenly, since usually the iron heats up 20-30C more in the wide part. Wait two minutes.

After this, remove the iron and in one motion, forcefully roll the stencil onto the foil fiberglass using a rubber roller for rolling photographs.

If during rolling the toner is crushed, that is, the tracks move to the side or change their shape, then you should reduce the amount of toner in the printer driver.

It is necessary that the center of the roller always moves along the center of the board. The roller handle must be held in such a way as to prevent the appearance of a force vector directed “around” the handle.

We roll the stencil tightly a few more times and press the resulting “sandwich” with something heavy, after laying down a newspaper folded several times in order to evenly distribute the weight.

The stencil should be rolled in the same direction each time. The roller begins to move from the place where the stencil is attached.

After about ten minutes you can remove the press and remove the stencil. This is what happened.

The excess part of the workpiece can be cut off and used next time.

Now you need to glue something to the back side of the board in any way so that you can later hold this board during etching. (I use hot glue.)

We etch the board in a ferric chloride solution.

How to prepare the solution?

If a jar of ferric chloride is unsealed, then most likely there is already a super-concentrated solution there. It can be poured into a pickling bowl and a little water added.

If the ferric chloride has not yet been covered with water, you can do it yourself. You can probably get the crystals themselves out of the jar, but don’t use heirloom silver for this.

Keep in mind that the etching process will not work in a highly concentrated solution, so once you have such a solution, you need to add a little water.

It is best to use a vinyl plastic photo bath as a dish, but you can use any other one.

The picture shows that the board floats on the surface of the solution due to its surface tension. This method is good because the etching products do not linger on the surface of the board, but immediately sink to the bottom of the bath.

At the very beginning of etching, you need to make sure that there are no air bubbles left under the board. During the etching process, it is advisable to check that the etching proceeds evenly over the entire surface of the board.

If there is any heterogeneity, then you need to activate the process with an old toothbrush or something similar. But this must be done carefully so as not to destroy the toner layer.

Particular attention should be paid to the holes in the contact pads. The areas where the etching process did not start immediately are lighter. In principle, it is enough to darken the entire surface and all holes at the very beginning of the process, and then success is a foregone conclusion.

In those places where the copper has been completely etched, the fiberglass begins to show through.

If the main part of the board was etched in 15 minutes, then you should not increase the total etching time more than twice, that is, more than 30 minutes. Further etching will not only reduce the width of the conductors, but may also partially destroy the toner.

Typically, all 0.5mm holes in the contact pads are etched in twice the time.

The motor turns a small eccentric, which creates vibrations in the solution (not necessary if you periodically lift and move the board).

Wash off the toner with a swab soaked in acetone.

This is what happened. On the left, the board is still covered with toner. The width of the tracks is 0.4mm.

We drill holes, not forgetting to periodically sharpen the drill.

Now you can remove the burrs formed on the copper during drilling. To do this, we first roll them up using a ball bearing secured in some convenient frame. In this case, it is better to place the board on a hard, flat surface. Then, using fine sandpaper, remove oxide from the surface of the copper, if it has formed.

We tin the workpiece, for which we first coat it with a layer of flux.

We cut the workpiece into separate boards.

At the request of the workers, I went to the stationery store and photographed the packaging with Self-adhesive labels. This paper is not suitable for thermal transfer. Although, if there is no other one, then you can use this one after some modification. More details in the next article about LUT.

On the left is the front side of the package, and on the right, respectively, is the back. On the back side there are options for placing self-adhesive labels on an A4 sheet. Large numbers are the number of labels of the same size placed on one A4 sheet.

All the above words about packaging are not directly related to the paper I selected. As it turns out, sellers use this packaging to store completely different types of paper.

Suspicions crept in when I bought different papers in different stores, which were taken out of the same package. The sellers said something about a manufacturer who changes the quality of paper like gloves. But today I talked with the owner of a small wholesale store and he told me that it turns out that sellers simply use the packaging as a container for paper, which initially does not have packaging. Or rather, there is packaging, but it’s just a thin transparent film.

So, the paper that turned out to be the most convenient for thermal transfer turned out to be produced by the Finnish company "Campas". And since there are no identifying marks on the small packaging, it is unlikely to be identified without testing.

As always, I print on a self-adhesive film backing. №333 . We take fiberglass, sawed off according to the format of the scarf sketch, and the sketch itself:

I clean the board with Pemolux until it shines, then wipe the board with ammonia to remove oxides and random fingerprints. It is recommended to do this, since after such treatment the toner will adhere better to the degreased surface.

Then I attach the sketch to the scarf and hold it, carefully align it, wrap it in a sheet of paper and iron it. I iron the workpiece while sitting, since it won’t be possible to press with body weight, otherwise the paths will blur:

After I iron it (the indicator on my iron lights up and I iron until it goes out), I cool the scarf to room temperature and put it under water:

We soaked for a minute and removed the paper backing; the photo shows that even the boundary track along the edges of the board, 0.1 mm wide, has disappeared:

This way we get a ready-made beautiful scarf for later, and we are happy with the result.

Let's continue the process. We clean the etched scarf from toner with a metal dish sponge, drill it and then remove small burrs from drilling with sandpaper, then take a simple and affordable alcohol-rosin flux (it’s easier to clean it with alcohol), cover the scarf with it and tin it with a regular soldering iron:

Afterwards I countersink the holes in the scarf, for the convenience of installing the parts, and even more carefully like this:

For visual convenience when installing parts, you can print a board mask on the same film. We apply it, aligning it with the mounting holes along the edges of the scarf so that the pattern matches the holes for the parts:

We wrap it in the same paper and iron it, remove the film backing, and in the end we get a beautiful and neat scarf ready for installing parts.

The process is very simple and not labor-intensive, and the resulting boards are of excellent quality, which is more than enough for home use. Good luck to everyone in mastering LUT technology! Compiled the instructions Igoran.

Discuss the article LUT TECHNOLOGY

There are many ways to apply designs to printed circuit boards at home, but each of them has its own pros and cons. For example, the photoresist method, which is quite expensive. Marker - requires extreme accuracy, time and patience. Using different varnishes can lead to even greater disappointments later. But each of these methods has the right to exist and, for example, I apply it depending on the final goal.

Today I decided to demonstrate a practical example of laser-iron technology for applying a pattern. I chose this method because my board will have 2 microcircuits and many millimeter traces. For example, drawing thin paths with a permanent marker will take a lot of time, but with the help of LUT this work will simply be eliminated.

Where did I start? Naturally from the design of the printed circuit board. Once the project was complete, I printed it out on a piece of coated paper from a magazine. The higher quality the paper, the fewer problems there will be when transferring the drawing. The most important thing is that the paper should be glossy and the toner should not fall off from it.

After that, I started cutting out the PCB. Usually it is advised to cut out the PCB with a margin, so that later the board can be adjusted if the pattern is applied crookedly, but I cut it one to one. If necessary, I simply remove the toner and reapply it. Accordingly, if you don’t have a laser printer at home, you need to print the board in several copies - just to be sure!

The textolite is cut out. Now it must be cleaned and degreased before applying the design. I do it again based on my experience - I clean the edges with sandpaper, clean the board with a hard sponge ( I don’t use sandpaper so as not to reduce the thickness of the already thin copper foil).I also degrease it in a unique way - I clean it with window detergent (some kind of Mr. Muscle), then rinse it with hot water and wipe it with a dry viscose rag. Then I take the textolite with my hands only by the ribs. In the end it becomes like this:

The textolite is ready to transfer the design onto it. I proceed like this - I cut out the printed project to the size of the board:

Now you need to take a large thick book, put textolite on it, cover it with 3-5 sheets of office paper and heat it with an iron for a minute. After this, we remove the sheets and carefully place the cut out pattern that should be translated onto the heated textolite. It instantly sticks to the board, so you need to act extremely carefully. Don’t forget that the PCB is now very hot and you need to use gloves when working.
After applying it to the textolite, smooth out the resulting “sandwich” from the center in all directions. Particular attention should be paid to the edges - they are where the most problems arise. Then we cover it again 3-5 sheets of office paper and heat with an iron, constantly moving it for uniform heating, about a minute or two.

Once finished, the textolite should cool down. After that, we place it in water so that the paper begins to limp and remove it under running water with your finger.

As a result, I got something like this:

It can be seen that in some places the toner has come off along with the paper. I compare the result with what I expected and correct the shortcomings with a marker. I secure the wiring so that the board can be removed from the solution.

This video lesson shows the implementation of LUT technology, which is used to make a double-sided printed circuit board. At home you can make compact ones using SMD elements. Here's an example charger For lithium ion battery 18650 taken from an old laptop battery, we will go through the process of creating a board from printing the drawing to turning it on.

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First of all, we draw a printed circuit board in the Eagle program for its subsequent manufacturing using laser-iron technology. About high-power lasers. The program is free for one- and two-sided applications. We upload each side of the signet in black and white in graphics editor and combine them to print on one sheet. We will print on tracing paper. But to prevent the printer from jamming it, you will need glue and an A4 sheet. We buy 40 sheets of tracing paper at the nearest stationery store.

First, look for the smooth side. We take out a sheet of paper and check where it slides more than usual, this is the top side. Now we bend the sheet of paper so that we can insert tracing paper. 1-1.5 cm is enough. We do not coat it too much with glue, as it will go inside the printer, and we glue the tracing paper evenly. If you make it crooked, the two sides won't match.

Preparing a “sandwich”. Now we fold the sheet at the top to place it in a manual feed printer. Insert with tracing paper facing up. We get a fingerprint. We cut out a large piece and fold it along the fold, aligning the two sides of the board to the light. Tracing paper is ideal for this. All holes are visible and can be accurately aligned. We glue the sheet together to make a pocket, and we will place the board in it. To do this, coat it with glue on both sides.

Preparing a board for implementing LUT technology

To prepare the board we will need cleaning powder. If it says it cleans copper, that's it. You can take another one, or even paste. GOI (but not sandpaper). We take the powder and begin to clean the board to a mirror shine. Once there are no dark spots left on the board, it can be placed in the pocket. Once cleaned, you can only pick it up by the edges so as not to leave greasy fingerprints.

We place the board in the finished pocket and align it so that the entire print falls on it. Everything is ready for ironing. It is better to take a simple one without steam. Temperature at maximum. Gently begin to iron over the entire area. The tracing paper sticks to the board and you can clearly see how the toner darkens. You don’t have to press too hard, but you need to iron both sides. Gradually the toner darkens and begins to bleed through the tracing paper. Once this has happened, everything is ready for the next operation. It is important not to overdo it, because the toner may spread and bottlenecks between the tracks may be flooded and will have to be cleaned up.

Now the tracing paper needs to be washed off. The toner will remain on the board, the paper will gradually come off. We cut it so that it all fits in the bath. We take ordinary water and throw the board there. We wait until it gets wet. After some time, the tracing paper begins to bubble and can be carefully removed. When wet, it comes off the board easily. The toner remains, covering all areas that we need to leave unetched. The tracing paper curls into lumps and gets wet. As a result, we get a beautiful, almost factory board.

It looks like it’s ready, but let’s take a magnifying glass and check how it turned out. It is clearly visible that there are pieces of paper left. The board will not be etched in these places. You need to remove the paper between the tracks. To do this we use a bristle brush. Moving along the paths, so as not to damage them, remove the remaining paper. When the board is dry, the places where the tracing paper remains are clearly visible, but this is not critical here. We drill a couple of holes on the side to insert the wire. She will help hold the board while we poison. We use ammonium persulfate. This is a rather aggressive substance and it is not recommended to dip your fingers in it. We take hot water from the tap. We dose it like this: one tablespoon of water per one teaspoon without a slide of persulfate. 5 spoons are enough for such a board. A water bath is also needed, since the etching reaction actively cools the solution.

Stir with a plastic or glass rod. And remember that if the solution gets on your clothes, it will leave holes. Place the board in the solution and stir for about five minutes. At first the solution is transparent, then gradually turns blue. This copper goes into solution in the form of copper sulfate. We see that the copper has brightened. There is very little left until it completely disappears. The layer is very thin and it will disappear now.

After about five minutes, the board is cleaned, there are small spots left that need to be cleaned with a brush to speed up the process. Using a soft brush, remove any remaining copper.

The metal tip is wrapped with electrical tape to prevent it from being etched. We take white spirit, which dissolves printer toner well. We need to clean the board to prepare it for tinning. You can also clean with acetone or use nail polish remover. After washing off the toner, the resulting product shines with copper traces.

Tinning

We will tin with Rose alloy. To do this, we need a ladle, which will be damaged and no longer suitable for anything. A little citric acid, gloves, tweezers and the alloy itself. Rose has a melting point of just under 100 degrees. It consists of small granules, one of which is enough to tinning a board. Add a spoonful of citric acid and a few tablespoons of salt. And we boil it. We throw a grain of alloy onto the board.

Rose, if the temperature is sufficient, will melt. We try to smear it with a cotton swab. If it doesn’t melt, then you need to add more salt to raise the boiling point. The alloy should be easily and effortlessly spread into a thin layer. We spread the alloy without lumps so that SMD elements can easily become. Now, within the framework of LUT technology, you can proceed to the next stage.

Drilling the board

Let's start drilling. A high-speed mini drill with a collet clamp was used. It allows you to clamp drills without distortion. Drills with a thicker shank are better. Drills of two sizes 0.5 and 0.8 are used; they can be taken for one size of collet clamp. It is better if you use a machine, but you can also carefully drill with a drill, it must be held strictly vertically. Then the holes on the top and bottom sides will fit exactly into the track seats. After drilling, you can make sure that both sides match perfectly.

Cutting the board

Now you can use regular metal scissors to cut the board to size. This can only be done if it is thin enough. The board is ready for soldering. To solder SMD elements, you need a special paste SOLDER PASTE, W001 is used, which is usually sold in tubes. Don't forget to store it in the refrigerator. We carry out soldering with a soldering hair dryer. Apply a drop of solder paste to each soldering point. Just a little bit is needed. If you don't have a needle, you can do this with a regular toothpick. A small drop is enough for soldering; if there are too many, you can end up shorting adjacent tracks.

Parts distribution

We put the details in place. You can arrange them roughly, but make sure they stay on the paste. When soldering, they are aligned using surface tension forces. Particular attention should be paid to microcircuits - they need to be placed more precisely. They, of course, also level out. But if they are placed crookedly, then you can get a short circuit in the tracks and either resolder them or remove the resulting “snot” with a soldering iron.

For our paste, a temperature of 230 degrees is enough; we set the minimum airflow so as not to blow our parts off the board. Heat each part until the solder melts. We see that the parts are aligned in place. Soldering with a hairdryer is a pleasure. It takes a long time to prepare, but the soldering itself is quick and high quality. In this case, you can solder the entire side of the board at a time. As a result, it turns out much faster than with a soldering iron.

Now the hardest part, three output parts that also need to be soldered, the rest are already in place. Before soldering the LEDs, it is a good idea to check their polarity. We switch the tester to the diode testing mode and, by the glow of the LED, determine where the plus and minus are. Let's take a tuning resistor, install it in place and solder it using a soldering iron. Since the board is double-sided, it is necessary to solder on both sides. The pins of the parts were also used to transmit a signal between the parties.

For convenience, it is better to use a “third hand” card holder, but you can do it without it, although it is less convenient. The result is this board for charging the battery, made using LUT technology. It is double-sided, there are both SMD and lead parts. Just look how convenient this thing is.
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If you don’t want to spend a lot of time making them, then the method described in the article is ideal for you. With the proper skill, it will fundamentally facilitate creativity. LUT technology can be divided into the following stages of printed circuit board manufacturing:

1. Let's create a drawing.
2. We make the preparation.
3. We transfer the drawing onto it.
4. We poison the workpiece.
5. Cleaning.
6. We do the drilling.
7. Tinning the board.

As you can see for yourself, in practice LUT technology can be implemented at home without significant problems and costs. You may not even have to acquire anything new, since everything you need for work can easily be found in the utility room. LUT manufacturing technology printed circuit boards well suited in cases where single production is carried out by one electronics enthusiast. Speaking about the advantages, first of all they remember the low cost, reliability and ease of work. Of course, these are not all the advantages, and the ones listed above were more than enough for many home craftsmen to make their choice in favor of LUT technology.

Create a drawing

There is a wide choice of tools: from pencil to special programs. When creating a printed circuit board, you must try to achieve the following goals:

1. Minimize the number of jumpers.
2. The paths relative to each other must be strictly perpendicular and parallel.
3. Compact installation.

When creating drawings, take into account the dimensions of the elements, the location of the pins of the parts and their dimensions. It is also necessary to ensure that high-current conductors have wider tracks. Creating a drawing can be compared to playing Tetris: you can mark out the elements as you please until you reach an ideal that will help bring LUT technology into reality. Jet printer(or laser) will help you make it physical, touch it with your own hands.

Making a blank

So, we have a drawing, and we can talk about the size of the board. Now you need to cut out the drawing, apply it to the textolite and direct it using a ruler. Is LUT technology not that complicated yet? Foil, that's what we need! Cut the foil PCB blank along the lines. Smooth the edges around the perimeter using a file and clean the surface. To do this, you can use fine sandpaper or a wire grater (the kind you use to clean dishes) along with detergent.

Transferring the drawing: general information

Let's say we printed an image on laser printer. And now we need to transfer it to the blank from paper. Place the resulting image onto the foil. Iron evenly, but use only light pressure. Peel off the paper, straighten and etch. If you are printing a picture, it is advisable to set the brightness to the minimum to create a very dark image. It is also advisable to set the toner density to high additional settings. This is necessary to avoid negative effects with gaps, which, alas, LUT technology has. The minimum size of the gaps is welcome; it is advisable that they should not be more than 0.2 millimeters.

Transferring the drawing: paper

This is a delicate thing, so its choice must be approached responsibly. Which samples are perceived better by LUT technology? The paper should be thick, you can use coated paper. Do not touch with oily fingers. It is not necessary to buy coated paper - you can take it. The main thing is that it is white on one side. Just in case, it is better to stock up on two copies of printed circuit boards. Cut it out and place it on the workpiece so that the pattern is on the foil side. We use a regular iron and don’t use steam. It is better to set the temperature to medium. We hold part of the drawing so that it does not move off the workpiece. Start to smooth the image smoothly, but do not allow it to move. Also, do not overdo it with force: if you press too hard, the toner will smudge, and with it the tracks. This can also happen if the iron is too hot. If the edges of the workpiece were poorly processed, then you will not be able to smooth the toner onto it well. When everything is ready, the workpiece should cool. Then place it in a bowl of warm water. Add a tablespoon of acetic acid. The paper will soften and begin to bubble. In ten minutes it will lag behind the toner. Rinse the resulting image with plenty of water. At first there may be isolated defects, but when working with the second copy, experience should be enough to avoid them. In general, LUT technology for manufacturing printed circuit boards may seem quite complicated, but this is only at first. By the way, the article above recommended having two papers, and this is not without reason. When starting out for the first time, many beginners make minor mistakes that result in smeared toner and other missteps. In order for the printed circuit board to turn out to be of higher quality, a recommendation was given to prepare a spare tire.

What to do if you don't have a laser printer?

You can also use nail polish applied with a thin brush for these purposes. In general, you can operate with at least one pencil and eraser. In these cases, LUT technology using glue is used for better results. When you wash off any remaining residue with water, make sure that there really is no residue left. Also, when you drill holes, make sure that the leads in them will feel good.

We etch the workpiece

Ferric chloride is used for this. When purchasing a substance, make sure it is in powder form. This ferric chloride is most suitable for our purposes. Although the option of using a mixture of table salt and copper sulfate is not excluded. But here it is necessary to maintain certain proportions. So, for one liter of boiled water you need to take two hundred grams of vitriol and add table salt until it stops dissolving. The resulting solution must be filtered. If it is heated to a temperature of 50 degrees Celsius, then it will take 15-20 minutes to bleed off the copper. But let's return to ferric chloride. It is necessary to fill the pickling container with water and add a heaped teaspoon. Be careful, since the chemical reaction that will occur will generate a lot of heat and the resulting solution may even splash a little. Mix everything well. Place your finger near the solution and make sure it is not too hot. Then place the workpiece in it, preferably with the foil down - so that it lies on the surface. At first she will swim and poison herself. In time she will drown. Then turn the printed circuit board over with the foil facing up and place it in the solution. Periodically, the container with it must be shaken so that dissolved copper is washed off the surface. If bubbles appear, you need to remove the board, wash it and continue etching. Depending on the temperature of the solution and its concentration, this process can take up to 1 hour.

Cleaning the workpiece from toner

Now we are faced with the problem of cleanliness. There are special solutions for this, but they do not find good reviews, and many people prefer mechanical method removing toner. To do this, it is recommended to use wire graters for washing dishes, which can provide a decent result.

Sverlovka

It is worth noting that to a large extent this is a matter of purely individual preference. But as recommendations, we can recommend the use of DPR micromotors and replaceable collet chucks. The drill can be selected at 0.8 millimeters - in most cases this is more than enough.

Tinning

Once you have drilled the PCB, you need to wash it with soap. Then scrub with a wire float, rinse again and dry. Then it must be coated with a solution of rosin in alcohol. You can also cover the board with active solder fat on Vaseline. As crazy as it may sound, it is a useful thing. Apply the fat in a thin layer, rubbing it well over the surface. must be placed so that the holes are not sealed. If this does happen, then take a wooden toothpick in your hands, heat the “dirty” place and clean it.

We can recommend POS-61 as a solder. It is designed to work with circuits in cases where overheating is unacceptable. And if this happens, the traces of the printed circuit board may peel off. In conclusion, we can say that the considered technique looks complicated. But this is a misleading opinion. Believe me, it will take you longer to create a good drawing than to create a printed circuit board. You can also give advice about the etching time: the fact is that if you leave the printed circuit board in the solution for several hours, then even the areas protected by toner will not be preserved. Therefore, it is very advisable to adhere to the time limits specified in the article.

Possibilities

It should be noted that LUT technology allows you to get good results in terms of work accuracy. So, with its help, some craftsmen have learned to etch letters and numbers, the size of which is 0.3 millimeters! Amazing quality of work! Of course, to achieve it, you will need training and experience, as in any field of activity.

Conclusion

It should be noted that the LUT technology for manufacturing double-sided printed circuit boards is not very different from the processes described in the article. Of course, you will have to make it a little more complicated and spend more time - but the end result will be worth it. LUT technology allows you to quickly and efficiently create printed circuit boards for all kinds of circuits. If at first something doesn’t work out, you should always remember that experience will allow you to sort it out. Therefore, you need to take into account your mistakes, learn from them and try again.